Ek, Monica

Abstract [en]

For the prodn. of cellulose derivs. raw material contg. high cellulose and low hemicellulose content is required and today's industrial state of the art is to use dissolving pulps produced by sulphite process or prehydrolisis kraft. This work, in contrast, focuses on the study of two different paper-grade kraft pulps from hardwood - birch and eucalyptus -- and the possibility to use it as raw material for the prodn. of cellulose derivs. There have been different studies that focus their investigations mainly on the decrease of the hemicellulose content. The aspects of accessibility and reactivity of cellulose towards solvents and reagents, however, are investigated far less although being key parameters when a homogenous substitution is desired for the prodn. of cellulose derivs. of high quality. In order to accomplish the requirements of a com. dissolving pulp, the kraft pulps were subjected to different enzymic treatments using com. enzymes, xylanase and monocomponent endoglucanase. Reactivity (Fock) was notably improved and the hemicellulose content decreased down to com. typical dissolving pulp values. Further on, the structural characteristics of the pulps will be studied by means of 13C-CP/MAS NMR and size exclusion chromatog. (SEC).